RIBA Core Curriculum
- Design, construction and technology
- General Awareness
Almost everyone knows that brick is one of mankind’s oldest and most durable building materials. Maybe that is the reason why it is sometimes overlooked in ‘modern’ architecture, despite its countless creative design possibilities.
In this section
- Brick durability and tolerances
- How different colours and textures are created
- Bond patterns and examples of how these are used
Why is brick sustainable?
Bricks are a versatile and durable building material with excellent life cycle performance, energy efficiency, high thermal mass and responsible manufacturing.
Brick and brick buildings are sustainable because they:
The BRE’s latest Green Guide to specification has assigned A+ accreditation to every external wall it rated containing brick.
Management systems help manufacturers to continually improve upon their performance.
With a lifespan of 500 years plus, any embodied energy within the brick from the manufacturing process is written off over a very long period, enabling brick to be a very sustainable product.
The BDA’s declaration of 500 years of durability and the service life of 150 years underlines the durability and legacy that you will be creating.
Brick offers a sense of stability, it is much more robust than many man-made materials and won’t rot, rust, erode or decay in ever changing weather patterns.
Brick is a solid, permanent and low maintenance material that provides lasting beauty and appreciating value – brick offers true longevity.
Achieving Different Colours
Different colours can be created in a number of ways using different raw materials, manufacturing techniques and processes.
Engobed surface treatment
Engobes are liquid colourings consisting mainly of clay minerals. The engobe is applied to the dried unfired bricks. During firing the engobe coating is sintered into the surface of the brick creating special colour effects.
Glazed surface treatment
A glassy solution is applied to the dried unburnt bricks. During the firing process, this applied surface coating fuses with the tile, forming a real glass coating. Unlike engobes, glazes are impervious to water.
Common Bond Patterns
Cavity walls originated in late 19th century and insulation was introduced into the building envelope in the 1970’s. Because the outer leaf is now only half a brick thick stretcher bond has become the most common bond in use. (least number of bricks per m²).
Popular during the 18th century Header bond often employed contrasting brick colours to give a decorative effect. This bond produces a fine, tight wall, but uses so many bricks that it is usually reserved for very high-quality buildings. It’s also used for curved brickwork, as the short faces are easier to build into undulating shapes.
Common Bond Patterns
From the beginning of the 18th century, the Flemish bond superseded English bond. This style has stretchers and headers alternating within each course. Flemish bonds can be replicated in the half-brick outer leaf of a cavity wall by using whole bricks as stretchers, while the headers are created by half bricks called bats or snap-headers.
This is the oldest pattern, and was commonly used until the end of the 17th century. A course of stretchers alternates with a course of headers. English Bond is considered stronger than Flemish bond, so continues to be used for civil engineering projects, such as bridges, viaducts and embankments.
Common Bond Patterns
Garden Wall Bonds
Laying stretchers uses up fewer bricks than laying headers however it is also less strong hence its use in traditional walled gardens and other modest structures.
In stack bond the bricks do not overlap and therefore the arrangement is inherently weak. To compensate for the lack of bonding, typically bed-joint reinforcement is built into every third bed-joint.
In general, reversible movements are caused by temperature changes. Irreversible expansion (caused by adsorption of water molecules by the fired clay brick) can be larger and continues, albeit at a reducing rate, for a period of years.
As a general rule in buildings, brickwork expansion joints should be provided every 10-12m maximum. This dimension reduces to 6m in boundary walls or brick faced parapets. In addition, movement joints should be provided where brickwork returns are less than 675mm, where there is a change in height or a change in surface finish.
The spacing and thickness of movement joints is related to the detailed design, length and height of the brickwork, together with any requirements for structural restraint. We would suggest that the Structural Engineer for the project reviews movement joint positions prior to construction.
An indication for normal storey height walls is that the joint width (in mm) should be at least equal to the joint spacing (in m) plus an allowance of typically 30% to allow for the compressibility of the filler and the performance of appropriate sealants – Thus movement joints at 10m centres will need to be approximately 13mm wide.
When brickwork is to be used to clad a reinforced concrete or timber frame, the design should make particular allowance for differential movement.
You’ve reached the end of the CPD. To make sure you’ve taken on board the key learnings of this course, please fill out the quick multiple choice Q&A below. This will certify that you have completed the CPD and provide you with an email certificate, which, if the course is accredited, you can share with RIBA.